1. Field of the Invention
The present invention relates to a heat moldable boot liner for use, for example, with a ski boot.
2. Description of the Related Art
Conventionally, moldable ski boot liners are made of a heat moldable material comprising a heat moldable foam interfaced between outer layers of felt fabric, and such heat moldable materials are readily commercially available.
In U.S. Pat. No. 5,673,448, issued Oct. 7, 1997, to Herbert Lang et al., there is disclosed a liner for a sports boot shell and a method of making a custom fitted liner for a sports boot shell which employ a single piece of thermoplastic foam material for the liner. More particularly, a blank made of the thermoplastic foam material is welded or stitched to connect together different portions of the edge of the blank so as to form an unfitted liner having a seam extending from its heel along its underside, and up and over the top of a foot portion of the liner to a gap which extends from a point situated centrally on the wearer's forefoot behind the wearer's toes and between the forward portion of the wearer's arch and the region above the ball of the wearer's foot. From this point, the gap extends upwardly between a pair of flaps or wings to a cuff at the top of the liner.
In use, the unfitted liner is heated in an oven and placed on the wearer's foot, the toes of which are padded to prevent the liner from subsequently holding the wearer's toes immobile. The wings are then wrapped around the wearer's lower leg, with one wing overlapped by the other, and a short nylon stocking is rolled over the liner, after which the wearer's foot with the liner on it is placed in a boot.
However, it has been found in practice that such a liner does not operate satisfactorily because the portions of the liner adjacent the gap, including the wings, tend to become adversely distorted as the wings are wrapped around the wearer's lower leg and as the foot and liner are inserted into the boot. Because the seam extends along the underside of the liner and because the underside of the liner is formed of deformable foam material, the shape of the liner is unstable as the liner is forced into its boot shell. Also, the foam molds itself into the soft parts of the underside of the wearer's foot during the molding operation, which causes pain and discomfort during subsequent use of the molded liner. It was also found that the heel portion of this prior liner tended to become dislocated during the molding operation, thus not only causing distortion of the lower portion of the liner but also causing dislocation of the cuff or top of the liner at the back of the wearer's leg, where the liner is required to be correctly positioned to protect the leg against the cuff or top of the boot shell. In addition, because this prior liner has only two wings, it is difficult to insert the wearer's foot with the liner after the molding of the liner has been completed and the liner material has hardened.